You could easily put a regulator on an air line and pressurize the bumper. The issue I see with that is, when the regulator fails, bye bye bumper.

his method of plugging the bumper would just blow out the plugs upon pressurization... from what I could tell.

It's a decent idea, but I probably wouldn't waste my time doing it for 7 gallons. If it was an expedition rig and could get up towards 20 gallons, then you're talking. but that is also about 80#s right?

Why not just fill the rollbar, and seal up the doors to fill them as well

1) Those water pumps are durable. They service the water system in every RV and camper. I also had one on a boat for a hot water shower and it worked great. I think pressurizing the tank creates more problems than it solves.

2) The comments about "only 7 gallons" are off base. That is 10% of what I can run my entire RV on for 5-6 days including washing dishes, showers, general sink useage and flushing a toilet. Having that much water on hand to wash hands and general purpose is more than adequate for a couple days on the trail. I've had to use waterless hand cleaner many times and a half bottle of bottled water is more than enough to rinse your hands off.
Washing an entire jeep to make it mud free? No. But being able to spray off a muddy windshield or plastic side window would be great. More than once we've carried a 2.5 gallon jug of water for just that + emergency drinking water. (not that I would want to drink water stored in the bumper

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